Nitro amines reduction

Although this reduction is more expensive than the Bnchamp reduction, it is used to manufacture aromatic amines which are too sensitive to be made by other methods. Such processes are used extensively where selectivity is required such as in the preparation of nitro amines from dinitro compounds, the reduction of nitrophenol and nitroanthraquinones, and the preparation of aminoazo compounds from the corresponding nitro derivatives. Amines are also formed under the conditions of the Zinin reduction from aromatic nitroso and azo compounds. 

Fusion of the imidazole ring to pyrrolo-benzothiadiazepine 340 can be achieved by straightforward TosMIC cycloaddition approach (Scheme 72, Section 4.2 (1994JHC1033)). An alternative sequence starts with the addition of nitromethane to the C-N double bond on the thiadiazepine ring, nitro group reduction and manganese oxide oxidation of the intermediate dihydroimidazole derived from amine 342 and tiiethyl ortho formate. 

The resin-bound perfluoroalkylsulfonyl linker is compatible with many common solid-phase reactions, such as tin dichloride-mediated aromatic nitro group reduction, trifluoroacetic acid-mediated tBoc deprotection, reductive amination reactions, acylation, and sulfonation. It is possible to perform several sequential synthetic reactions on the nonflate resin so that multistep syntheses can be carried out. The solid-phase approach provides an operationally simple, inexpensive, and general protocol for the cleavage... 

Protocols of peptide chemistry and, to some extent, biooligomer synthesis (e.g., nucleotides, saccharides) are valuable sources of information on this topic with regards to solid-phase synthesis peculiarities. Here we focus on a particular functional group transformation, which takes the role of depro-tecting a masked functionality, namely the nitro-to-amine reduction. This approach provides a versatile tool for planning multistep derivatizations of heterocycles, as exemplified in Fig. 15.45... 

The synthesis of the tetracyclic intermediate 49 was therefore studied in the hope that it might further cyclize to the desired lycorine skeleton. Birch reduction of o,p-dimethoxyphenethylamine led to the amine 50 which was converted into 51, giving rise in turn upon hydrolysis to 49. Its structure rests on physical data. Ordinary methods for nitro group reduction seemed to also destroy the 289-nm chromophore, but hydrogen transfer (a-phellandrene and Pd/C) gave a product which analyzed for the product of nitro reduction to amine in 49, the mass spectrometric data also being in agreement. The product was, however, not affected by diazotization, and, on the basis of spectral data, was... 

Thus, animation, or reaction with ammonia, is used to form both aliphatic and aromatic amines. Reduction of nitro compounds is the traditional process for producing amines, but ammonia or substituted ammonias (amines) react directly to form amines. The production of aniline by animation now exceeds that produced by reduction (of nitrobenzene). 

Table 5. //-Hydroxy Amines by Oxidative Photoaddition of A-Nitroso and A-Nitro Amines, Followed by Reduction ...

Certain aliphatic diamines have been prepared by reduction of nitro amines with hydrogen or aluminum amalgam. The starting materials are readily obtained by the reaction of nitroparaffins with formaldehyde and amines (method 444). 

Partial reduction of aromatic polynitro compounds leads to nitro amines. The most successful reagents are the alkali metal or ammonium sulfides in aqueous alcoholIn some instances, sodium bicarbonate combined with sodium sulfide gives better results because of the formation of sodium hydrosulfide, which is believed to be the main reducing agent. Also, aqueous methanol is preferred to aqueous ethanol. Nitro compounds that are sparingly soluble in alcohol solutions may be reduced by hydrogen sulfide in pyridine solution. ... 

Aqueous reductions are useful for amine synthesis. Organic reducing agents (N H or formic acid) reduce amides or imines . Active metals in acid reduce nitro groups . Reduction of Ph3PNBr with I ... 

It is soluble in alcohol, ether, benzene, and ligroine, insoluble in water. Acids colour the alcoholic solution violet, the salts being precipitated as grey crystals. It dissolves in concentrated sulphuric acid with a green colour, changing through blue to violet on dilution with water. By action of amyl nitrite a nitros-amine, M.P. 119° 5, is obtained. On reduction it yields aniline and paramidodiphenylamine. 

Many cyclic amines are prepared by reduction of cyclic imines (see Section 1.20.3), or amides (see Section 1.20.4). Nitro-, amine- and carboxyl-substituted cyclic amines are formed by Mannich condensations (see Section 1.20.6). 

Only a few of the many aromatic diamino ethers used to prepare macrocycles will be mentioned here. A reduction process has been used to prepare aromatic diamines from nitro- and azide-containing ethers. The preparation of an aromatic diamine using known methods was reported by Glinka (1982), who treated an aromatic nitro halide with hexamethylenetetraamine followed by hydrolysis to give an aromatic nitro amine. The nitro amine was... 

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